1. Field of the Invention
The invention relates to field-effect transistors (FETs) and to methods for fabricating FETs.
2. Discussion of the Related Art
The FET is a very important device in contemporary electronics. In many FETs, the condition of the surface of the semiconductor channel has an important effect on the operation of the FET. In particular, a semiconductor surface and any adjacent dielectric can trap charges. Such trapped charges could reduce the density of mobile charge carriers in the semiconductor. For that reason, high densities of trapped charge densities adversely affect operation of an FET.
Indeed, the conventional fabrication of an inorganic FET often includes a passivation step, which reduces the density of such trapped charges. In silicon FETs, the passivation step includes annealing the silicon surface of the FET's channel in the presence of hydrogen. The hydrogen chemically bonds to dangling bonds from surface silicon atoms thereby neutralizing such dangling bonds as charge traps.
Though the passivation step enables the fabrication of crystalline silicon-based FETs with excellent operating characteristics, crystalline silicon-based FETs have one property that is undesirable for some electronics applications. In particular, crystalline silicon-based FETs are mechanically rigid and are typically fabricated on rigid crystalline substrates. In some applications, it is desirable that the FETs and associated substrate be mechanically flexible. While organic FETs are flexible and have been fabricated on flexible substrates, their operating characteristics are typically substantially inferior to those of crystalline silicon-based FETs. It is desirable to have another type of FET that is mechanically flexible and has operating characteristics superior to those of ordinary organic FETs.